Solar Charge Controller

pianotuna wrote:
Hi Mex,

As usual, you are the voice of sanity.

MPPT is for folks who have either money to burn, have run out of roof space, or wish to extract ever possible watt of power from their system.

PWM remains the way to go for battery charging (small systems). I do think that temperature compensation is a must do, especially where it is cold or hot. For that reason, I do not endorse the solar 30 unit that Niner uses to good effect.

MEXICOWANDERER wrote:
I get dizzy re-reading these three pages.

What bubbles up to the surface is a couple of smaller batteries and hinges for the panels.

This is not MPPT territory, sorry.

I am usually one of the first to state what works for me, and I am pretty good about including the caveat... YMMV. Everyone's needs are different.

wbwood wrote:
Just saw that Renogy has the same stuff on eBay but for a little less, still with free shipping.

What would be the recommended length of cable for a portable set up? Would 20' suffice or would just go ahead and go longer right from the start?

how/where do you camp?? If your almost always are near direct sun and out of trees/shade, no need for long cable.

Where we camp, that's seldom the case. However, with either PWM or MPPT, AND having the controller near the battery (NEVER at the panel). you can have LONGGGGGG cable runs. I have two 50' and one 25' cable. Each is 30A power cords, with the ground paralled with the neutral since you only need two conductors. I run the panels in series with a MPPT controller. (240W total, 3 panels)
Our Daughters in Laws have have two 50' #12 sections with a PWM controller. same thing, with the ground and neutral shorted together.

In each case when we need the 100ft cable, current loss is minimal, a few tenths of an amp over a 10ft run or so based on some experiements we did.

I made up cable sections using the anderson 50A connectors. very robust, low resistance connectors. then roll out what I need.

This lets us pick our best campsite and then run cable for the panels rather than have the cable/panel dictate our camp location.

pianotuna wrote:
Hi ktmrfs,

How much for setting a broken leg when I fall off the roof while hurrying to de tilt the panels in a wind storm.

The only way I'd have tilt system is if it were powered, or if I could manipulate it easily from the ground. Far better to put on an extra panel to make up for the losses, at least for me.

Tilts one advantage of a portable system. Growing legs and disapearing is a disadvantage.

Just saw that Renogy has the same stuff on eBay but for a little less, still with free shipping.

What would be the recommended length of cable for a portable set up? Would 20' suffice or would just go ahead and go longer right from the start?

Hi ktmrfs,

How much for setting a broken leg when I fall off the roof while hurrying to de tilt the panels in a wind storm.

The only way I'd have tilt system is if it were powered, or if I could manipulate it easily from the ground. Far better to put on an extra panel to make up for the losses, at least for me.

pianotuna wrote:
mPPT is for folks who have either money to burn, have run out of roof space, or wish to extract ever possible watt of power from their system.

guilty as charged.

MEXICOWANDERER wrote:
I get dizzy re-reading these three pages.

What bubbles up to the surface is a couple of smaller batteries and hinges for the panels.

This is not MPPT territory, sorry.

MPPT is for higher voltage massive panels (but cheaper per watt), long runs of panel to controller wire and critical little bit extra charging at sunup and sundown. MPPT on a small system would be like a Goodyear Blue Streak racing tire on a wheelbarrow. Just my humble opinion.

Agreed.

And, having the ability to tilt the panels, especially as you go north and/or need solar in the winter, offers way more gain than an MPPT controller. A flat (horizontal) panel in northern states or fall winter captures way less solar energy than a panel reasonably tilted.

You can see a 25-50% or so increase in output current going from a flat panel to a reasonable tilt. Tilt should be approximately latitude + solar declination. Put a cardboard tube on the panel end on and adjust the panel for minimum shadow and check the current then lay the panel flat and see the difference.

Down where Mex is, probably not as big a deal, near the equator the panel wants to be near horizontal anyway. Where we are (Oregon) panels want to be around 45-60 degrees. Even in the southern U.S. you'd probably want a 30-45 degree tilt depending on time of year.

Hi Mex,

As usual, you are the voice of sanity.

MPPT is for folks who have either money to burn, have run out of roof space, or wish to extract ever possible watt of power from their system.

PWM remains the way to go for battery charging (small systems). I do think that temperature compensation is a must do, especially where it is cold or hot. For that reason, I do not endorse the solar 30 unit that Niner uses to good effect.

MEXICOWANDERER wrote:
I get dizzy re-reading these three pages.

What bubbles up to the surface is a couple of smaller batteries and hinges for the panels.

This is not MPPT territory, sorry.

Hi Niner,

He does need to investigate whether that is "the one" or not.

pianotuna wrote:
Hi,

Try this one? 30 amp controller.

steveh27 wrote:
Of course! I would not have asked otherwise. There are many listed & I don't want to play roulette. If you have one that works well for you why not share? Thanks.

Piano, it will, of course, be all your fault when that unit doesn't work out for him, for what ever reason.